The field of the invention is systems and methods for installing fiber optic cable or similar cables or conduits underground. More specifically, the invention relates to the installation of such cable or conduit into pressurized pipelines, such as natural gas pipelines.
With the tremendous growth of the Internet and telecommunications services in general, there has been a commensurate growth in the need to carry larger and larger volumes of data over existing and newly added communication lines. Existing copper-based communications lines, however, have a limited carrying capacity, or bandwidth, as compared to fiber optic cable. Conventional copper wires also suffer from the problem that the wire bundles are quite large as compared to their fiber optic counterparts. Additional copper wires could be installed to increase the overall capacity of a communications or data network. However, fiber optic cable is now preferred within the communications industry due to its significant advantages over copper wires.
Currently, in many countries, there are existing large scale fiber optic backbones that stretch across wide areas. Unfortunately, many businesses and consumers cannot connect to this fiber optic backbone because they are located some distance away from the main line. If copper-based lines are connected to the fiber optic backbone, the high speed and high bandwidth advantages of fiber optic cable are lost. In order to take advantage of the increased speed and bandwidth provided by fiber optic cable lines, shorter segment fiber optic lines need to be laid to reach these businesses and consumers.
Unfortunately, it is a difficult and costly procedure to lay fiber optic cable in developed regions where infrastructure such as roads, utilities, and the like are already in place. For example, it can be costly to obtain the requisite right-of-ways or easements from numerous different property owners. It can also be very costly to dig trenches to lay fiber optic cable. In addition, it is also often necessary to obtain the approval of various state and local government agencies before such work can begin. This can significantly increase the overall cost and delay the completion of the installation.
Existing gas pipelines have been considered as one potential conduit that can be used to carry fiber optic cable. By using existing gas pipelines, there is no need to obtain numerous right-of-ways or easements, since the fiber optic cable simply resides within the pipeline. In addition, long trenches do not have to be dug to lay the fiber optic cable. However, using gas pipelines as a route for fiber optic cable typically requires that sections or all of the pipeline be shut down for an extended period of time for installation of the cable. Even if the gas pipeline is not completely shut down, existing techniques interrupt the normal flow of gas.
In the past, various systems and methods have been used to install cable or conduit in liquid pipelines. These known systems and methods have met with varying degrees of success. However, these liquid pipeline systems are generally not well suited for use in gas pipelines. Providing adequate seals in gas pipelines is typically more difficult and requires sealing techniques which are different from those used with liquids. In addition, as liquids are much denser or heavier than gas, the large current or flow forces available in a liquid pipeline for carrying a drogue or similar devices, are not available in gas pipelines. In addition, the buoyant forces of a liquid pipeline, which can help to center and convey a drogue or conduit line, are not available in a gas pipeline. Hence, installing a conduit or cable into a gas pipeline presents unique engineering challenges. On the other hand, techniques which work for gas pipelines will generally also be useful with liquid pipelines.
Accordingly, there is a need for a relatively quick and inexpensive systems, tools, and methods of installing fiber optic cable, or conduit which can be used to house the cable, into existing pipelines such as natural gas pipelines.
In a first aspect of the invention, and extractor system for installing a cable or conduit into a pipeline includes a receiver assembly and a nose assembly. The nose assembly has a nosepiece and the receiver assembly has a latching mechanism for latching onto the nosepiece. The receiver assembly also preferably has a guide section for guiding the nosepiece into the receiver assembly. In an alternative aspect, the nose assembly has a u-joint to better facilitate engagement between the nose piece and the receiver assembly.
In a second aspect of the invention, a duct rod assembly for use in installing a cable or conduit into a pipeline includes a duct rod, a nose piece on the duct rod, a gland body having a seal, with the duct rod extending through the seal in the gland body. A receiver assembly includes a latching mechanism for engaging onto the nose piece, when the nose piece and receiver assembly are engaged together. The gland body may optionally further include a threaded section adapted to engage onto a pipeline fitting.
In a third aspect, an extractor system for use in installing a cable or conduit into a pipeline includes an end plug attached to the cable or conduit and an end nose having a coupling feature. A coupler has a receptacle adapted to couple onto the end plug. The end plug preferably has a rounded end nose, a conical guide collar, and a coupler groove between the end nose and the guide collar. A conical guide may be provided on the receptacle to engage with the conical guide collar on the end plug.
In a fourth aspect, an extractor tool for extracting an end fitting through a pressure seal during installation of a cable or conduit into a pressurized gas pipeline includes an extractor tube, a handle attached adjacent a first end of the extractor tube, a lock rod axially displaceable within the extractor tube, and a tube collar section at a second end of the extractor tube. A socket is axially displaceable within the tube collar section. The socket is attached to the lock rod. Retainers in the socket move to engage an end fitting on a cable, conduit, or duct rod, when the end fitting is moved into the tube collar section.
In a fifth aspect a receiver assembly for engaging and extracting an end fitting on a cable, a conduit, or a duct rod, includes a pull bar, a handle attached adjacent a first end of the pull bar, and a socket extending into a sleeve attached to a second end of the pull bar. An insert is axially displaceable within the socket and biased into a first position by an insert spring. A sleeve spring urges the sleeve away from the second end of the pull bar and over the socket. A locking element is provided between the sleeve and the socket. A pawl is pivotally attached to the pull bar and moveable from a first position, wherein the sleeve is positioned at least partially over the pawl, to a second position, wherein the pawl locks the sleeve against movement towards the first end of the pull bar.
In a sixth aspect, a method for installing a cable or conduit into a pipeline includes the steps of routing a first line having a first end fitting into the pipeline, from a first location. A second line having a second end fitting is routed into the pipeline from a second location, until the second end fitting contacts the first end fitting, at an intermediate position within the pipeline, between the first and second locations. The first end fitting is then engaged with the second end fitting. The first line is pulled back until the second end fitting is adjacent to the first location. The end fittings may be an end plug and a mating receptacle, or they may be grappling fittings or components, or spiral fittings or components. Various equivalent end fittings which can engage and hold onto each other, while the lines are pulled through the pipeline, may be used. This method substantially doubles the pipeline routing length of conventional duct rod or conduit pushing methods, since two lines are routed or pushed towards each other from opposite ends of a pipeline segment.
The invention resides as well in sub-combinations of the methods and systems described. The tools and fittings described also constitute separate inventions to be claimed, apart from systems and methods. These items may also be provided as a kit.
It is an object of the invention to provide methods and systems for installing fiber optic or similar cable or conduits into existing pressurized gas pipelines without interrupting the flow of gas in the pipeline.